1. Technical Field
This invention relates to timepieces, and more particularly, to an electrical device for displaying time.
2. Description of Related Art
The history of clocks is very long, and there have been many different types of clocks over the centuries. The first way that people could tell the time was by looking at the sun as it crossed the sky. When the sun was directly overhead in the sky, it was the middle of the day, or noon. When the sun was close to the horizon, it was either early morning (sunrise) or early evening (sunset). The oldest type of clock is a sundial clock, also called a sun clock. They were first used around 3,500 B.C. The next great advance in timekeeping occurred in about 3450 B.C. when a primitive hourglass was invented. This device was basically a bowl with a hole in the bottom. Water dripped through the hole slowly as the day wore on and grooves cut into the side of the bowl measured the passage of time. The hour glass had many advantages over sundials, because they would work on cloudy days and at night.
The Greeks divided the year into twelve parts that are called months. They divided each month into thirty parts that are called days. Their year had a total of 360 days, or 12 times 30 (12×30=360). Since the Earth goes around the Sun in one year and follows an almost circular path, the Greeks decided to divide the circle into 360 degrees. The Egyptians and Babylonians decided to divide the day from sunrise to sunset into twelve parts that are called hours. They also divided the night, the time from sunset to sunrise, into twelve hours. Twelve is about the number of moon cycles in a year, so it is a special number in many cultures. The hour is divided into 60 minutes, and each minute is divided into 60 seconds. The idea of dividing the hour and minute into 60 parts comes from the Sumerian sexagesimal system, which is based on the number 60. This system was developed about 4,000 years ago. The first practical clock was driven by a pendulum. It was developed by Christian Huygens around 1656. By 1600, the pendulum clock also had a minute hand. One problem with pendulum clocks is that they stopped running after a while and had to be restarted. The first pendulum clock with external batteries was developed around 1840. By 1906, the batteries were inside the clock.
Quartz crystal clocks were invented in 1920. Quartz is a type of crystal that looks like glass. When you apply voltage or electricity and pressure, the quartz crystal vibrates or oscillates at a very constant frequency and the vibration moves the clock's hands very precisely. The next great advancement in timekeeping was in 1967 when the atomic clock, which used the oscillations of cesium-133 atoms, was developed to precisely to tell time. Almost all clocks use a round face to display the time. While these time displays have had a relatively long history, what is needed is a new and novel method of displaying the time.